Introducer sheath having a multi-layer hub

ABSTRACT

An introducer assembly includes an elongate sheath sized for insertion into a blood vessel of a patient and a hub. The hub can be coupled to a proximal portion of the sheath and can include a first hub portion and a second hub portion. The hub can include various features to facilitate breaking apart or separating the introducer assembly from a patient. For example, the first hub portion can have a first notch which can facilitate breaking, splitting, or fracturing the hub. The second hub portion can partially surround the first hub portion and can include two wings and an opening disposed above the first notch. The first hub portion can be formed from a first material and second hub portion can be formed from a second material. In some embodiments, the second material can be stiffer than the first material to facilitate fracturing the hub.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. provisional application No.62/298,171, filed Feb. 22, 2016, the content of which is herebyincorporated herein by reference in its entirety.

BACKGROUND

Patients with cardiac ailments are sometimes treated with a percutaneousmechanical circulatory support device, also commonly referred to as aheart pump, configured to assist the natural cardiac pump function or toreplace natural cardiac pump function by a continuous pumping operation.These heart pump assemblies can be introduced surgically orpercutaneously during a cardiac procedure through the vascular system,such as through blood vessels. In one common approach, pump assembliesare inserted via a catheterization procedure through the femoral arteryusing an introducer sheath.

The introducer sheath can provide a reliable access point for theintroduction of heart pump assemblies as well as a wide range ofdiagnostic and therapeutic interventional catheter-based devices. Theintroducer sheath can be inserted into an artery or vein, and the pumpcan be advanced through the introducer sheath into the patient. Theintroducer sheath can then be separated into two halves along a breakwall and peeled away while the pump, catheter, and/or guidewire is leftin place. This allows physicians to perform clinical procedures thatrequire separation/removal of the introducer sheath without disturbingthe position of a pump, catheter, guidewire, and/or other device thathas been introduced into and should remain positioned inside of thebody.

As percutaneous heart pumps have become larger and more sophisticated,the introducer sheaths for introduction of the pumps into the body havealso necessarily become larger. The larger introducer sheath and hubassembly require a greater breaking force to split the hub of theintroducer sheath (e.g., because the thickness of the break wall isgreater). The increased break force can make fracturing the hubdifficult and less reliable. Furthermore, the increased break force canlead to abrupt breaks of the hub which may undesirably jostle, dislodge,or damage the pump, and/or may in some cases cause discomfort or injuryto the healthcare physician administering treatment.

SUMMARY

Disclosed herein is an introducer sheath having a multi-layer hub forpercutaneous insertion of a heart pump. The hub can include two or morehub portions formed of different materials so as to reduce the breakforce required to split the peel-away introducer. The hub has a firsthub portion and a second hub portion partially surrounding the first hubportion. The first hub portion includes one or more notches along whichthe hub is configured to split. The second hub portion includes wings ortabs positioned on either side of the hub which are used as leverage forapplying the break force. The first hub portion may be formed of a softmaterial having a low ultimate strength, while the second hub portionmay be formed of a relatively stiff material having an ultimate strengthhigher than that of the first hub portion. In such a configuration, thesoft first hub portion allows the hub to be easily split along thenotches in the first material, while the stiff second hub portion hasstiff wings which provide improved leverage during breaking. The stiffwings do not bend or flex excessively when a force is applied, butinstead transfer applied loads to the notches, thereby facilitatingsplitting of the introducer. The stiffer wings also reduce the amount ofelastic energy that is stored when force is applied to the wings duringsplitting of the introducer hub. This reduces the sudden release ofelastic energy when the hub is split, thereby reducing the risk ofdisplacing or damaging the pump, or causing discomfort or injury to thepatient or physician. Thus, by using two hub portions of differingmaterial properties, the systems, methods, and devices described hereincan facilitate splitting of the peel-away introducer sheath. Bymaintaining a low break force, the multilayer hub enables use of widerbore introducer sheathes which would otherwise be too difficult tosplit.

The second hub portion may be over-molded on the first hub portion. Theovermolding may form a hemostatic bond between the first hub portion andthe second hub portion. To strengthen the bond between the two portions,the first hub portion may also include ridges or grooves over which thesecond hub portion is molded. This can increase the amount of torquethat the second hub portion can transmit to the first hub portionwithout failure of the bond. Additionally, the second hub portion mayinclude an opening above the one or more notches in the first hubportion. This opening allows the first hub portion to easily split inthe region of the notch or notches, thus preserving the low break forceof the hub.

In one aspect, an introducer assembly comprises an elongate sheath and ahub. The elongate sheath is sized for insertion into a blood vessel of apatient and includes a longitudinal axis. The hub is coupled to aproximal portion of the sheath and comprises a first hub portion and asecond hub portion. The first hub portion comprises a first notch. Thesecond hub portion partially surrounds the first hub portion andcomprises two wings and an opening disposed above the first notch. Thefirst hub portion comprises a first material and the second hub portioncomprises a second material, wherein the first material differs from thesecond material. In some implementations, the first material has a firstultimate strength and the second material has a second ultimatestrength. In certain implementations, the second ultimate strength isgreater than the first ultimate strength. In some implementations, thefirst material has a first stiffness and the second material has asecond stiffness, the second stiffness being greater than the firststiffness.

In some implementations, the first notch is oriented parallel to thelongitudinal axis of the elongate sheath. In certain implementations,the hub is configured to break at the first notch along the direction ofthe longitudinal axis of the elongate sheath. In some implementations,the elongate sheath has a longitudinal scoring parallel to thelongitudinal axis of the elongate sheath. The elongate sheath may beconfigured to tear along the longitudinal scoring parallel to thelongitudinal axis of the elongate sheath.

In some implementations, the first hub portion includes ridges. In someimplementations, the first hub portion and the elongate sheath form ahemostatic bond. In certain implementations, the wings comprise a wideface and a narrow face and the wide face is normal to the longitudinalaxis of the elongate sheath. In some implementations, the narrow face ofthe wings is normal to the longitudinal axis of the elongate sheath. Insome implementations, the first hub portion further includes a secondnotch. In some implementations, the first hub portions include a firstridge and a second ridge which define edges of the first notch.

In some implementations, the first material has a hardness of about 45Shore D. In certain implementations, the second material has a hardnessof about 68-72 Shore D. In some implementations, the introducer hub hasa minimum diameter of about 9 Fr. In other implementations, theintroducer hub has a minimum diameter of about 26 Fr. In certainimplementations, the first hub portion has a minimum thickness of about0.1 mm at the first notch. In some implementations, the first hubportion has a maximum thickness of about 0.3 mm at the first notch.

In some implementations, the thickness of the first hub portion at thefirst notch is variable along a length of the notch. In someimplementations, the thickness of the first hub portion at the firstnotch is greatest at a proximal end portion of the first notch. In someimplementations, the thickness of the first hub portion at the firstnotch is between about 0.01 inches and 0.012 inches at the proximal endof the first hub. In some implementations, the thickness of the firsthub portion at the first notch is between about 0.004 inches and 0.006inches at a distal end portion of the first hub.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects and advantages will be apparent uponconsideration of the following detailed description, taken inconjunction with the accompanying drawings, in which like referencecharacters refer to like parts throughout, and in which:

FIG. 1 shows a top view of an illustrative introducer hub assembly;

FIG. 2 shows a perspective view of an illustrative introducer hubassembly;

FIG. 3 shows a perspective view of an illustrative first hub portion ofan introducer hub assembly;

FIG. 4 shows a perspective view of an introducer hub assembly includingfirst and second hub portions;

FIG. 5 shows a perspective view of a notch of the introducer hubassembly of FIG. 2;

FIG. 6 shows an end view of an illustrative introducer hub assemblyhaving multiple layers of material;

FIG. 7 shows a perspective view of an illustrative introducer hubassembly with wings positioned in a transverse orientation relative to acentral longitudinal axis of the introducer hub; and

FIG. 8 shows an introducer hub assembly inserted into a blood vessel ofa patient with a percutaneous pump extending therethrough.

DETAILED DESCRIPTION

To provide an overall understanding of the systems, methods, and devicesdescribed herein, certain illustrative embodiments will be described.Although the embodiments and features described herein are specificallydescribed for use in connection with introducer sheaths for percutaneousinsertion of heart pumps, it will be understood that all the componentsand other features outlined below may be combined with one another inany suitable manner and may be adapted and applied to other types ofintroducer sheaths, other types of cardiac assist devices, or for thedelivery of any suitable catheter, guide wire, surgical tool, or medicaldevice.

The apparatus described herein includes an introducer and a hub assemblyfor the introducer (where the introducer can be used, e.g., forpercutaneous insertion of a heart pump). The hub can have a first hubportion and a second hub portion partially surrounding the first hubportion. The first hub portion can include a notch along which the hubcan be configured to fracture or split. The second hub portion caninclude wings or tabs positioned on opposite sides of the hub and may beused as leverage for applying the break force. The first hub portion canbe formed of a soft material having a low ultimate strength, while thesecond hub portion can be formed of a relatively stiff material havingan ultimate strength that is higher than an ultimate strength of thefirst hub portion. In such a configuration, the soft first hub portioncan allow the hub to be easily fractured or split along the notch in thefirst material, while the wings of the stiff second hub portion provideimproved leverage during breaking. The stiffness of the wings isselected so that the wings do not bend or flex excessively when pressureis applied and instead transfer applied loads to the notches, therebyfacilitating splitting of the introducer. The stiffer wings can alsoreduce the amount of elastic energy that is stored when force is appliedto the wings during splitting of the introducer hub. This reduces thesudden release of elastic energy when the hub is split, thereby reducingthe risk of displacing or damaging the pump, and/or injuring the patientor physician. Thus, by using two hub portions with differing materialproperties, the systems, methods, and devices described herein canfacilitate splitting of the introducer sheath. By maintaining a lowbreak force, the multilayer hub enables use of introducer sheatheshaving larger dimensions and/or a larger bore which would otherwise betoo difficult to split.

The hub assembly can be manufactured in various ways and can includedifferent combinations of features. For example, the second hub portioncan be over-molded on the first hub portion. The over-molding can form abond between the first hub portion and the second hub portion thatprevents blood from passing through the interface between the first hubportion and the second hub portion. In particular, the bond formed bythe over-molding may be a chemical and/or molecular bond. If the firsthub portion is formed of a polymer similar to a polymer from which thesecond hub portion is formed, the polymer chains of the two materialsmay cross-link at the interface between the first hub portion and secondhub portion.

Alternatively, the first and second hubs can be molded separately andthen bonded together using any technique known in the art, such as usingchemical adhesive. In either instance, the first hub portion may alsoinclude ridges or grooves to strengthen the bonding between the firstand second hub portions by increasing the surface area for polymercross-linking and/or to provide a mechanical interlock between the firstand second hub portions. This can increase the amount of force that thesecond hub portion can transmit to the first hub portion without failureof the bond. For another example, the second hub portion may include anopening above the one or more notches in the first hub portion. Thisopening allows the first hub portion to easily split in the region ofthe notch, thus preserving the low break force of the hub. Bymaintaining a low break force, the systems, methods, and devicesdescribed herein thus allow introducer hubs to be made larger toaccommodate large heart pumps while still breaking apart withapplication of a reasonable amount of force.

FIG. 1 shows a top-down view of the introducer hub assembly 50 includingan elongate sheath 2 and a hub 10. The elongate sheath 2 is sized forinsertion into a blood vessel of a patient and has a longitudinal axis8. The hub 10 includes a first hub portion 12 having a first notch 14,and a second hub portion 16 having an opening 20 and two wings 18 a and18 b. The opening 20 is disposed above the first notch 14. The firstnotch 14 in the first hub portion 12 is in some implementations alignedwith or at least partially parallel to the longitudinal axis 8 of theelongate sheath 2. The second hub portion 16 partially covers the firsthub portion 12. In some implementations, the second hub portion 16 isover-molded onto the first hub portion 12. The second hub portion 16includes an opening 20 above the first notch 14 which exposes the firstnotch 14.

The first notch 14 formed in the first hub portion 12 provides a breakwall at which a crack may be initiated in the hub 10 by applying forceto the wings 18 a and 18 b. The first notch 14 may be formed in a firstmaterial having a relatively low ultimate strength break force.Furthermore, the first notch 14 may be formed such that a thickness ofthe first material at the bottom of the first notch 14 permits breakingof the hub 10 at the first notch 14 at a reasonably low force.Additionally, the shape of the notch 14 may concentrate stress tofacilitate splitting of the hub 10 along the notch 14. In someimplementations, the first hub portion 12 has a minimum thickness at thefirst notch 14 of 0.1 mm. In some implementations, the first hub portion12 has a maximum thickness of 0.3 mm at the first notch 14. In someimplementations the first hub portion 112 has a thickness at the firstnotch 14 of 0.075 mm, 0.08 mm, 0.09 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25mm, 0.3 mm, 0.35 mm, or any other suitable thickness.

The second hub layer 16 partially surrounding the first hub layer 12allows the wings 18 a and 18 b to be formed from a stiffer material. Thestiff wings 18 a and 18 b allow a healthcare professional to applyforce, such as a manual force, to break the hub 10 at the first notch14. After the hub is broken, the wings 18 a and 18 b can be pulled apartand used to peel away the introducer hub assembly 50 from the patientand any devices or guidewires extending through the vessel. In someimplementations, the second hub portion 16 can be over-molded over thefirst hub assembly 12.

During use, the introducer hub assembly 50 facilitates insertion of aheart pump or other medical object into a blood vessel of a patient. Theintroducer hub assembly 50 is designed as a peel-away introducer. Theelongate sheath 2 is inserted into a blood vessel of the patient and theheart pump is advanced through the hub 10 and through the elongatesheath 2 into the patient. During removal of the introducer hub assembly50, the wings 18 a and 18 b can be grasped and a first force is appliedby a user, e.g. a healthcare professional, toward the user to break thehub 10 along the first notch 14. A second force may then be applied in adirection opposite the first force to break the hub 10 along a secondnotch (not shown). The introducer hub assembly 50, including the hub 10and elongate sheath 2, is then peeled away, leaving the heart pump orother medical object undisturbed within the blood vessel of a patient.

FIG. 2 shows a perspective view of an illustrative introducer hubassembly 100. The introducer hub assembly 100 includes an elongatesheath 102 and a hub 110. The hub 110 includes a first hub portion 112and a second hub portion 116. The first hub portion 112 includes a firstnotch 114, a proximal end portion 115, and a distal end portion 117. Thesecond hub portion 116 includes an opening 120 above the first notch 114and two wings 118 a and 118 b. The elongate sheath 102 includes alongitudinal axis 108 and an internal diameter 104 which is sized toallow a heart pump or medical device to be inserted through the elongatesheath 102 and into a blood vessel of a patient. The internal diameter104 of the elongate sheath may be 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm orany other suitable diameter. In some implementations, the inner diameterof the elongate introducer body 105 is compatible with devices that are9 French (3 mm), 10 French (3.33 mm), 11 French (3.67 mm), 12 French (4mm), 13 French (4.33 mm), 14 French (4.67 mm), 15 French (5 mm), 16French (5.33 mm), 17 French (5.67 mm), 18 French (6 mm), 19 French (6.33mm), 20 French (6.67 mm), 21 French (7 mm), 22 French (7.33 mm), 24French (8 mm), 26 French (8.67 mm), or any other suitable diameter. Thefirst hub portion 112 lies closest to an outer surface 106 of theelongate sheath 102. The first hub portion 112 includes a first notch114 which is oriented to be parallel to the longitudinal axis 108 of theelongate sheath 102. The first hub portion 112 also includes a firstridge 128 a and a second ridge 128 b which extend up from surface of theelongate sheath 106, defining the first notch 114. The second hubportion 116 partially surrounds the first hub portion 112 except at anopening 120 over the first notch 114. In some implementations, theopening 102 is also over the first ridge 128 a and second ridge 128 b ofthe first hub portion 112 defining the first notch 114. The second hubportion 116 includes two wings 118 a and 118 b which extend outward oneither side of the hub 110. Each of the two wings 118 a and 118 b isconstructed to include a wide face 124 a and 124 b and a narrow face 125a and 125 b. The two wings 118 a and 118 b may be oriented in a varietyof directions. In some implementations, a wide face 124 a and 124 b ofthe wings 118 a and 118 b may be positioned to be normal to thelongitudinal axis 108 of the elongate sheath 102. In otherimplementations, a narrow face 125 a and 125 b of the wings 118 a and118 b may be positioned to be normal to the longitudinal axis 108 of theelongate sheath 102.

After the heart pump or medical device has been inserted into thepatient, the introducer hub assembly 100 can be separated at the hub 110along the length of the first notch 114 and at the elongate sheath 102along the length of the longitudinal scoring 122. The wings 118 a and118 b are designed to be gripped by a healthcare professional forremoval. The healthcare professional applies force to the first andsecond wings 118 a and 118 b to part (e.g. “peel-away”) the introducerassembly 100. This separates the hub 110 at the first notch 114 and thelongitudinal scoring 120, fracturing/breaking the hub 110 and elongatesheath 102 in half. In some implementations, the wings 118 a and 118 bare designed to be pressed in a downward motion toward the elongatesheath 102 to break the hub 110 at the first notch 114. In suchimplementations, the wide face 124 a and 124 b of the wings 118 a and118 b may be oriented to be normal to the longitudinal axis 108 of theelongate sheath 102. In other implementations, the narrow face 125 a and125 b of the wings 118 a and 118 b may be oriented to be normal to thelongitudinal axis 108 of the elongate sheath 102 and may be designedsuch that forcing the two wings 118 a and 118 b toward each otherfacilitates the breaking of the first notch 114. Once the hub 110 hasbeen broken at the first notch 114, each of the wings 118 a and 118 bmay be peeled away from each other to remove the hub 110. The elongatesheath 102 may also include a longitudinal scoring 122 parallel to thelongitudinal axis 108 in line with the first notch 114 in the hub 110.The elongate sheath 102 may be configured to tear along the longitudinalscoring 122 in order to peel-away when the hub 110 is broken and peeledaway by pulling the wings 118 a and 118 b away from each other. Thefirst hub portion 112 may include a second notch (e.g., 126 in FIG. 4)opposite the first notch 114. In such cases, the second notch is alsofractured by pulling the wings 118 a and 118 b away from each other. Theelongate sheath 102 may further include a second longitudinal scoring(not shown) at which the hub 110 may be broken and torn.

The first hub portion 112 and the second hub portion 116 may becomprised of material having different material properties. The firsthub portion 112 may have different surface properties, durometer,ultimate or tensile strength, modulus of elasticity or other materialproperties than the second hub portion 116. The second hub portion 116may be more rigid, stiffer, tougher, or harder, relative to the firsthub portion 112. The different material properties of the first hubportion 112 relative to the second hub portion 116 allow the hub 110 tobe increased in size to accommodate larger pumps and medical deviceswhile still able to be efficiently broken by the medical personnel'shands. In some implementations, the material forming the second hubportion 16 has an ultimate strength that is greater than an ultimatestrength of the material forming the first hub portion 12. In someimplementations, the material forming the second hub portion 16 has arigidity that is greater than a rigidity of the material forming thefirst hub portion 12. In certain implementations, the first materialforming the first hub portion 12 has a hardness of 45 Shore D. In someimplementations, the first material may have a hardness of 30 Shore D,35 Shore D, 40 Shore D, 45 Shore D, 50 Shore D, or any other suitablehardness. In some implementations, the second material forming thesecond hub portion 16 has a hardness of 60 Shore D, 65 Shore D, 68 ShoreD, 70 Shore D, 72 Shore D, 75 Shore D, or any other suitable hardness.

FIG. 3 shows a perspective view of the first hub portion 112 of theintroducer hub assembly 100 of FIG. 2. The first hub portion 112 isattached to the elongate sheath 102 at a proximal end of the elongatesheath 102 and includes a first notch 114 defined by a first ridge 128 aand a second ridge 128 b, and ridges 130. The first notch 114 may bealigned with a longitudinal scoring 122 on the elongate sheath 102parallel to the longitudinal axis 108 of the elongate sheath 102. Thefirst hub portion 112 may define the first notch 114 with a minimumthickness 132 of the first hub portion 112 at the first notch 114. Thefirst notch 114 may be further described by the first ridge 128 a andthe second ridge 128 b. The ridges 130 may be constructed as ribbedfeatures or grooves oriented in a direction or many directions on thefirst hub portion 112. The ridges 130 allow the first hub portion 112 tomore securely interface with an over-molded layer, promoting rigidity ofthe structure during breaking of the introducer hub assembly 100. Theridges 130 provide a mechanical interlock between the first hub portion112 and the second hub portion (e.g., 116 in FIG. 2) to transmit torqueapplied to the wings (e.g., 118 a and 118 b in FIG. 2) to the first hubportion 112. The force applied to the wings (e.g., 118 a and 118 b inFIG. 2) is thus transmitted to a break wall of the first notch 114. Thefirst hub portion 112 may form a hemostatic bond with the elongatesheath 102, in particular if the first hub portion 112 and the elongatesheath 102 are both comprised of a same material.

FIG. 4 shows a perspective view of the introducer hub assembly 100according to certain embodiments. The introducer hub assembly 100includes an elongate sheath 102, the first hub portion 112 having afirst notch 114 and a second notch 126, and the second hub portion 116having two wings 118 a and 118 b. The first hub portion 112 has aproximal end portion 115 and a distal end portion 117. The first hubportion 112 is connected to the elongate sheath 102 at the distal endportion 117. The second hub portion 116 partially covers the first hubportion 112. In some implementations, the second hub portion 112 coversthe first hub portion 116 in near entirety except at an opening 120above the first notch 114. In some implementations, the second hubportion may cover a smaller portion of the first hub portion 112. Asdescribed above, the first and second hub portions can be formed usingvarious techniques (e.g., over-molding the second hub portion 116 ontothe first hub portion 112 or molding the first and second hub portions112, 116 separately and then fixing them together using adhesives).

The first notch 114 is oriented parallel to a longitudinal axis 108 ofthe elongate sheath 102 and is in line with a longitudinal scoring 122of the elongate sheath 102 such that the hub assembly 100 may functionas a peel-away introducer upon breaking of the hub 110 at the firstnotch 114 and tearing of the elongate sheath 102 along the longitudinalscoring 122. The hub 110 has a second notch 126 in the first hub portion112 shown on an opposite side of the hub 110 as the first notch 114. Thesecond notch 126 further facilitates breaking of the hub 110 for removalof the hub assembly 100. The second notch 126 may be defined in asimilar way as the first notch 114 and may also be oriented to beparallel to the longitudinal axis 108 of the elongate sheath 102. Thelongitudinal sheath 102 may include a second longitudinal scoring (notshown) which is aligned with the second notch 126 and is opposite thelongitudinal scoring 122.

During removal of the introducer assembly 100 a force is applied to thewings 118 a and 118 b pushing the wide faces 124 a and 124 b of thewings 118 a and 118 b toward each other. As the force is transferredthrough the material and applied toward the first notch 114, there is acompressive force in the hub at the first notch 114 and a tension at thesecond notch 126 such that both the first notch 114 is broken.Application of a force to the wings in the opposite direction breaks thesecond notch 126. The first notch 114 in the first hub portion 112 andthe minimum thickness 132 of the first hub portion 112 at the firstnotch 114 and second notch 126 allows the hub 110 to be easily broken atthe first notch 114 and second notch 126. The first hub portion maycomprise a material having a low ultimate strength to further facilitatethe breaking of the hub 110 at the first notch 114 and the second notch126. The second hub portion 116 may comprise a material having a higherultimate strength than the material of the first hub portion 112. Insome implementations, the first hub portion 112 and the second hubportion 116 may be comprised of polyether block amide (e.g., PEBAX®manufactured by Arkema Group) or similar material. The second hubportion 116 includes the wings 118 a and 118 b which are able towithstand the force required to break the hub 110 without flexing,facilitating breaking of the hub. Further, the second hub portion 116may have an increased thickness 134 where it covers the first hubportion 112 in order to provide rigidity to the hub 110.

FIG. 5 shows a perspective view of the first notch 114 in the introducerhub assembly 100 of FIGS. 1 and 2. The first notch 114 is formed in thefirst hub portion 112 having a minimum thickness 132 at the first notch114. The first notch 114 runs the length of the first hub portion 112from the proximal end portion 115 to the distal end portion 117. Thefirst notch 114 is further defined by a first and second ridge 128 a and128 b formed in the first hub portion 112. The second hub portion 116partially covers the first hub portion 112 and includes an opening 120over the first notch 114. The second hub portion 116 may have anassociated thickness 134. In some implementations the first hub portion112 has a minimum thickness 132 of 0.1 mm at the first notch 114. Insome implementations, the first hub portion 112 has a maximum thicknessof 0.3 mm at the first notch 114. In certain implementations, the firsthub portion 112 has a thickness 132 at the first notch 114 of 0.075 mm,0.08 mm, 0.09 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, orany other suitable thickness.

In some implementations, the first hub portion 112 has a variablethickness 132 at the first notch 114 along the length of the first notch114. In certain implementations, the first hub portion 112 has a greaterthickness 132 at the proximal end portion 115 of the first hub portion112 than at the distal end portion 117. The distal end portion 117 ofthe notch 114 nearest the connection between the hub 110 and theelongate sheath 102 can have the maximum stress concentration duringfracture and may therefore be the intended initiation point of thebreak. Thus, a relatively thin break wall of the notch 114 at the distalend portion 117 reduces the force required to start the break.

In some implementations, a hemostatic valve (not shown) is included inthe hub 110 at the proximal end portion 115. The proximal end portion115 in which the valve is disposed must be strong enough to support thehoop stress induced in the hub 110 from compression of the valve. Thisis especially important when objects, such as catheters, are insertedthrough the hub, increasing the hoop stress. In some implementations,the thickness 132 of the notch 114 at the proximal end portion 115 isgreater than the thickness of the notch 114 at the distal end portion117. The increased notch thickness at the proximal end portion 115reinforces the hub 110 in the area of increased hoop stress. In someimplementations, the thickness of the notch 114 at the distal endportion 117 is around 0.004″-0.006″. In some implementations, thethickness of the notch 114 at distal end portion 117 is 0.003″, 0.0035″,0.004″, 0.0045″, 0.005″, 0.0055″, 0.006″, 0.0065″ or any other suitablethickness. In some implementations, the thickness of the notch 114 atthe proximal end portion 115 of the first hub portion 112 is around0.010″-0.012″. In some implementations, the thickness of the notch 114at the proximal end portion 115 of the first hub portion 112 is 0.0095″,0.010″, 0.0105″, 0.011″, 0.0115″, 0.012″, 0.0125″ or any other suitablethickness. In some implementations, the change in thickness may occurover a smooth transition. In some implementations, the change inthickness may occur via a series of steps of increased thickness.

The use of the softer material to form the first hub portion 112 allowsthe variation in the thickness of the notch 114 along its length. Thisis because the thickness of the notch 114 is constrained on the upperend by the maximum allowable break force and on the lower end bymanufacturing tolerances. If the notch 114 is too thick, it cannot bebroken. But if it is too thin, it cannot be easily manufactured bytraditional processes (e.g., injection molding). The use of a softermaterial for the first hub portion 112 increases the upper limit for thenotch thickness because it enables sufficiently low break force atgreater notch thicknesses. This increase in the upper limit of the notchthickness affords a range within which the notch thickness can vary,thereby enabling variation in the notch thickness along the length ofthe notch. Thus, the use of a different material for the first hubportion 112 compared to the second hub portion 116 enables varying thethickness of the notch along the length of the notch.

FIG. 6 shows a perspective view along the longitudinal axis 108 of theelongate sheath 102 of an introducer hub assembly 100 according tocertain embodiments. The introducer hub assembly 100 includes theelongate sheath 102 sized to fit a heart pump or medical device and tobe inserted into a blood vessel of a patient. The elongate sheath 102 issurrounded by the first hub portion 112 including a first notch 114 atwhich point the thickness of the first hub portion 112 may be at aminimum thickness 132. A second hub portion 116 surrounds the first hubportion 112 and includes an opening 120 over the first notch 114. Insome implementations, the first notch 114 may be further defined by aridge or extension of the first hub portion 112 (shown as 128 a and 128b in FIG. 5). In some implementations, a base of the first notch 114 maybe defined by the first hub portion 112 and the second hub portion 116may further define an upper portion of the first notch 114. The secondhub portion 116 also includes a first wing 118 a and a second wing 118b.

FIG. 7 shows a perspective view of an alternative embodiment of theintroducer hub assembly 200 with wings 218 a and 218 b having atransverse orientation. The introducer hub assembly 200 includes anelongate sheath 202 having an inner diameter 204 sized to allow thepassage of a heart pump into a blood vessel of a patient and alongitudinal axis 208, a first hub portion 212 having a first notch 214,and a second hub portion 216 having an opening 220 over the first notch214 and first and second wings 218 a and 218 b.

The first wing 218 a and the second wing 218 b are oriented such thatwide faces 224 a and 224 b of the wings 218 a and 218 b are normal tothe longitudinal axis 208 of the elongate sheath 202. In thisembodiment, the introducer hub assembly 200 is fractured and separatedfrom the patient using a different technique than for the embodiment ofFIG. 1. More specifically, to break the hub 210 at the first notch 214,the wide faces 224 a and 224 b of the wings 218 a and 218 b are forcedtoward the elongate sheath 202. The hub 210 fractures along the firstnotch 214 and along a second notch (not shown) opposite the first notch214. Additionally, the elongate sheath 202 tears at a longitudinalscoring 222 and at a second longitudinal scoring (not shown) which isopposite the longitudinal scoring 222. The introducer hub assembly 200is now broken in half and can be removed, leaving the device, catheteror guidewire in place in a blood vessel of a patient.

FIG. 8 shows the introducer hub assembly 100 of FIGS. 2, 4 and 6inserted into a blood vessel of a patient 140 with a percutaneous pump142 extending partially therethrough. The percutaneous pump 142 caninclude various features, such as a pump head 144 and a catheter body146. The percutaneous pump 142 may be an intravascular heart pump, aheart pump driven by a flexible shaft and a motor positioned external tothe patient's body, a heart pump including an implantable motor, a heartpump having an expandable pump rotor, or any other suitable pump. Theintroducer hub assembly 100 is advanced into the blood vessel 140through the blood vessel aperture 150 in the direction indicated byarrow 148 and then the percutaneous pump 142 is inserted through theintroducer hub assembly 100 and into the blood vessel 140. The bloodvessel 140 may be a femoral artery, and the blood vessel aperture 150may be an arteriotomy.

After the percutaneous pump 142 has been advanced through the introducerhub assembly 100 the introducer hub assembly 100 may be removed and insome implementations replaced by a device appropriate for longer-termuse. To remove the introducer hub assembly, a healthcare professionalmay grasp the first and second wings 118 a and 118 b and apply a forceto the wings 118 a and 118 b in a direction either toward the elongatesheath 102 or a direction radial to the elongate sheath 102 forcing afirst wing 118 a toward the second wing 118 b depending on theorientations of the first and second wings 118 a and 118 b relative tothe elongate sheath 102. In the orientation of wings 118 a and 118 bshown, the healthcare professional applies a radial force (radial withrespect to the elongate sheath 102) to the wings 118 a and 118 b to movethem toward each other. The first and second wings 118 a and 118 b areformed of a stiff material of the second hub portion 116 and do not flexwhen force is applied. The applied force is transmitted from the wings118 a and 118 b to the first notch 114 and the second notch 126 (notshown). The minimum thickness 132 of the first hub portion 112 at thefirst notch 114 and second notch 126 allows the hub 110 to be broken atthe first notch 114 and second notch 126. In some implementations, thehealthcare professional applies a second radial force in an oppositedirection in order to break the second notch 126. The longitudinalscoring 122 on the elongate sheath 102 allows the sheath to separatealong the longitudinal axis 208, and the hub 110 and elongate sheath 102may be peeled away in two pieces leaving the percutaneous pump 142 inplace in the blood vessel 140.

The foregoing is merely illustrative of the principles of thedisclosure, and the apparatuses can be practiced by other than thedescribed embodiments, which are presented for purposes of illustrationand not of limitation. It is to be understood that the apparatusesdisclosed herein, while shown for use in percutaneous insertion of heartpumps, may be applied to apparatuses in other applications requiringhemostasis.

Variations and modifications will occur to those of skill in the artafter reviewing this disclosure. The disclosed features may beimplemented, in any combination and subcombination (including multipledependent combinations and subcombinations), with one or more otherfeatures described herein. The various features described or illustratedabove, including any components thereof, may be combined or integratedin other systems. Moreover, certain features may be omitted or notimplemented.

Examples of changes, substitutions, and alterations are ascertainable byone skilled in the art and could be made without departing from thescope of the information disclosed herein. All references cited hereinare incorporated by reference in their entirety and made part of thisapplication.

I claim:
 1. An introducer assembly comprising: an elongate sheath sizedfor insertion into a blood vessel of a patient, the sheath having alongitudinal axis, wherein the elongate sheath consists of a firstmaterial; a hub coupled to a proximal portion of the sheath, the hubcomprising: a first hub portion having a first notch, the first hubportion partially encompassing the proximal portion of the elongatesheath; a second hub portion partially encompassing the first hubportion, the second hub portion comprising: two wings; and an openingdisposed above the first notch; and wherein the first hub portionconsists of the first material and the second hub portion comprises asecond material, the first material differing from the second material.2. The introducer assembly of claim 1, wherein the first material has afirst ultimate strength and the second material has a second ultimatestrength, the second ultimate strength being greater than the firstultimate strength.
 3. The introducer assembly of claim 1, wherein thefirst material has a first stiffness and the second material has asecond stiffness, the second stiffness being greater than the firststiffness.
 4. The introducer assembly of claim 1, wherein the firstnotch is oriented parallel to the longitudinal axis of the elongatesheath.
 5. The introducer assembly of claim 1, wherein the hub isconfigured to break at the first notch along a direction of thelongitudinal axis of the elongate sheath.
 6. The introducer assembly ofclaim 1, wherein the elongate sheath further comprises a longitudinalscoring parallel to the longitudinal axis of the elongate sheath.
 7. Theintroducer assembly of claim 6, wherein the elongate sheath isconfigured to tear along the longitudinal scoring parallel to thelongitudinal axis of the elongate sheath.
 8. The introducer assembly ofclaim 1, wherein the first hub portion includes ridges.
 9. Theintroducer assembly of claim 1, wherein the first hub portion and theelongate sheath form a hemostatic bond, wherein the hemostatic bond isconfigured to prevent blood from flowing between the first hub portionand the elongate sheath.
 10. The introducer assembly of claim 1, whereinthe wings each comprise a wide face and a narrow face, and the wide faceis normal to the longitudinal axis of the elongate sheath.
 11. Theintroducer assembly of claim 1, wherein the wings each comprise a wideface and a narrow face, and the narrow face is normal to thelongitudinal axis of the elongate sheath.
 12. The introducer assembly ofclaim 1, wherein the first hub portion includes a first ridge and asecond ridge which define edges of the first notch.
 13. The introducerassembly of claim 1, wherein the first material has a hardness of about45 Shore D.
 14. The introducer assembly of claim 1, wherein the secondmaterial has a hardness in the range of about 68-72 Shore D.
 15. Theintroducer assembly of claim 1, wherein the hub has a minimum diameterof about 9 Fr.
 16. The introducer assembly of claim 1, wherein the firsthub portion has a minimum thickness of 0.1 mm at the first notch. 17.The introducer assembly of claim 1, wherein the thickness of the firsthub portion at the first notch is variable along a length of the notch.18. The introducer assembly of claim 17, wherein the thickness of thefirst hub portion at the first notch is greatest at a proximal endportion of the first hub portion.
 19. The introducer assembly of claim18, wherein the thickness of the first hub portion at the first notch isbetween about 0.01 inches and 0.012 inches at the proximal end portionof the first hub portion.
 20. The introducer assembly of claim 18,wherein the thickness of the first hub portion at the first notch isbetween about 0.004 inches and 0.006 inches at a distal end portion ofthe first hub portion.